7408 (74LS08, 74HC08): the quad AND gate chip, live

The 7408 is a 14-pin chip with four independent 2-input AND gates: each output nY is 1 only when both of its inputs nA and nB are 1. The 74LS08 and 74HC08 share the same pinout as the 7400, with VCC on pin 14 and GND on pin 7. This live chip has all four gates.

AND gates are how one signal enables another: data passes through only while an enable is 1, which is the idea behind a decoder's outputs, a multiplexer's data paths and the carry of a half adder. The 7408 has the same pin positions as the 7400, so the two are easy to swap on a breadboard, but they are different gates: inside, an AND gate is a NAND followed by an inverter, which in CMOS is six transistors and two gate delays (see the CMOS AND gate). That is one reason logic built from NAND gates is so common. All 256 combinations of the eight inputs are checked before the page is built.

Live circuit: click the inputs to toggle them and watch the outputs update. It runs the real simulator, right here on the page.

Open this circuit in the lab →

What you need

4× AND: four independent 2-input AND gates, Y = A AND B, numbered 1 to 4 as on the datasheet

Step by step

Power the chip: VCC on pin 14 and GND on pin 7 (5 V for the 74LS08; 2 V to 6 V for the 74HC08).
Each gate has two inputs, nA and nB, and an output nY; find their pins in the pinout below.
Tie every unused input to VCC or GND: TI's 74HC datasheets say unused inputs must be terminated, because a floating CMOS input can drift and draw current.
Set 1A = 1 and 1B = 1: 1Y goes to 1. With either input at 0, 1Y stays 0.

7408 pinout

Pin	Name	Pin	Name
1	1A	14	VCC
2	1B	13	4B
3	1Y	12	4A
4	2A	11	4Y
5	2B	10	3B
6	2Y	9	3A
7	GND	8	3Y

AND truth table (each gate)

A	B	Y
0	0	0
0	1	0
1	0	0
1	1	1

Pin numbers are for the DIP and SOIC packages (TI SN74HC08 datasheet, checked 2026-10-25). See also the AND truth table.

You can also read the full theory in the lesson on the AND gate. Prefer to build it yourself from scratch? Open the digiwleea lab and place the gates on the canvas, or start from the logic gate simulator.

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Each of these is one step from a transistor to a working CPU. Build every gate from CMOS transistors and work all the way up in the free digiwleea lab, with the free theory reference alongside.

Open the 7408 quad AND gate chip in the lab →

Frequently asked

What is a 7408 chip?

A 14-pin chip with four independent 2-input AND gates. VCC is pin 14 and GND pin 7; the pinout is the same as the 7400, 7432 and 7486.

What is the difference between the 74LS08 and the 74HC08?

Same gates and pinout. The 74LS08 is TTL for a 5 V supply; the 74HC08 is CMOS, works from 2 V to 6 V and uses less power.

Is an AND gate faster than a NAND gate?

Usually not. In CMOS an AND gate is a NAND gate plus an inverter, so it has an extra stage of delay and two more transistors. NAND and NOR are the natural single-stage gates.

How do I make a 3-input AND gate from a 7408?

Chain two gates: AND the first two inputs in one gate, then AND that output with the third input in a second gate.